Answer:
Researchers initially built up the geologic time scale by considering rock layers and record fossils around the world. With this data, researchers put in Earth's stone layers in request by relative age. Afterward, radioactive dating decided the supreme age of the divisions in the geologic time scale.
If the atoms that are bonding have identical electronegativities, then it's a completely nonpolar covalent bond. This doesn't happen in the real world unless the two atoms are of the same element. In a practical sense, any two elements with an electronegativity difference less than 0.3 is considered to be nonpolar covalent.
As the difference between the atoms increases, the covalent bond becomes increasingly polar. At a polarity difference of 1.7 (this changes depending on who you ask) we consider it no longer to be a covalent bond and to be the electrostatic interactions characteristic in an ionic compound.
Just so you know, you shouldn't take these values as exact. ALL interactions between adjacent atoms involve some sharing of electrons, no matter how big the difference in electronegativity. Sure, you wouldn't expect much sharing in KF, but there's a little sharing of electrons anyway. There's certainly no big cutoff that happens at a difference of 1.7 Pauling Electronegativity units.
<span>One important area of DNA research is that of genetics and medical research. Due to our discovery of DNA, our ability to actually diagnose diseases early on has been vastly improved. In addition, we have been able to better assess a person's genetic susceptibility to specific diseases. In doing so, we have also paved the pathway to formulate brand new drugs to treat these diseases. In fact, drugs can essentially be custom made to complement a person's personal biochemistry and genetic makeup. For those diseases that were previously considered lethal and where treatment was either non-existent or largely unsuccessful, the discovery of DNA has essentially led to breakthrough drugs and treatments for patients with serious illnesses.</span>
